本實驗研究85Rb原子與85Rb2分子在光偶極阱中的碰撞，透過吸收影像法量測85Rb F=2原子團的生命周期，來觀察原子與分子碰撞的行為，估計在光偶極阱中85Rb2分子的數量。在實驗中，使用非單頻的高功率Fiber雷射 (波長1080 nm,輸出功率為20W) 作為光偶極阱的光源，並透過成像系統，做了螢光法與吸收影像法，對Crossed dipole trap中的銣原子做基本量測。在系統中，光偶極阱約載到了1.13x105個原子，平均密度約9.7x1011個/cm3，在基態F=3的原子團溫度約在400 ，生命週期小於100 msec；在基態F=2的原子團溫度約44 ，生命周期約100msec~200msec。透過光結合的方法產生85Rb2分子，同時與存在85Rb的原子團載入光偶極阱中，此時量測85Rb(F=2)原子團生命週期約78msec。

In experiment, we observe 85Rb atoms and 85Rb2 molecules collision in crossed dipole trap by using absorption image method to measurement the Rb atoms lifetime and calculate the numbers of 85Rb2 molecules in a crossed dipole trap. We use high power laser (non-single frequency Fiber laser, 1080 nm, 20W) for a laser source of crossed dipole trap. The crossed dipole trap can be seen from CCD image system, we use absorption image and fluoresce method to measure lifetime, atom number, and temperature in a crossed dipole trap. The number of atoms in crossed dipole trap is about 1.13x105 atoms, the average density is atom/cm3.The atoms in ground state F=3, the temperature is about 400 and the life time less than 100 msec. The atoms in ground state F=2, the temperature is about 44 and the lifetime is 100~200 msec. By using photoassociation method to generate 85Rb2 molecules, and load in crossed dipole trap with Rb atoms at the same time, the lifetime of atom in ground state (F=2) is 79msec.

[1] T. Hansch and A. Schalow, Opt. Comm. 13, 68 (1975).
[2] Steven Chu, L. Hollberg, J. E. Bjorkholm, Alex Cable, and A. Ashkin. Phys. Rev. Lett. 55,48(1985)
[3] E. L. Raab, M. Prentiss, Alex Cable, Steven Chu, and D. E. Pritchard . Phys. Rev. Lett. 59.2631(1987)
[4] M. H. Anderson, J. R. Ensher, M. R. Matthews, C. E. Wieman, and E. A. Cornell. Science,269,198(1995)
[5] A. Fioretti, D. Comparat, A. Crubellier, O. Dulieu, F. Masnou-Seeuws, and P. Pillet. Phys. Rev. Lett. 80.4402(1998)
[6] A. Fioretti, D. Comparat, A. Crubellier, O. Dulieu, F. Masnou-Seeuws, and P.
Pillet “Formation of Cold Cs2 Molecules through Photoassociation”, Phys. Rev. Lett. 80, 4402 (1998).
[7] Nicolas Vanhaecke, Wilson de Souza Melo, Bruno Laburthe Tolra, Daniel Comparat, and Pierre Pillet, “Accumulation of Cold Cesium Molecules via Photoassociation in a Mixed Atomic and Molecular Trap”, Phys.Rev. Lett. 89, 063001 (2002)
[8] E. A. Donley, N. R. Claussen, S. T. Thompson, C. E. Wieman “Very-high-precision bound-state spectroscopy near a 85Rb Feshbach resonance”, Nature 417, 529 (2002).
[9] H. L. Bethlem, G. Berden, F. M. H. Crompvoets, R. T. Jongma, A. J. A. van Roij
and G. Meijer “Electrostatic trapping of ammonia molecules”, Nature 406, 491 (2000)
[10] J. M. Doyle, B. Friedrich, J. Kim and D. Patterson “Buffer-gas loading of atoms and molecules into a magnetic trap”, Phys. Rev. A 52, R2515(1995)
[11] H. R. Thorsheim, J. Weiner, and P. S. Julienne, Laser-induced photoassociation of ultracold sodium atoms," Phys. Rev. Lett., 58,2420(1987).
[12] T. Takekoshi, B. M. Patterson, and R. J. Knize. Phys. Rev. Lett., 81,5105(1998)
[13] A. N. Nikolov, E. E. Eyler, X. T. Wang, J. Li, H. Wang, W. C. Stwalley, and P. L. Gould. Phys. Rev. Lett., 82,703(1999)
[14] A. N. Nikolov, J. R. Ensher, E. E. Eyler, H. Wang, W. C. Stwalley, and P. L. Gould . Phys. Rev. Lett. 84, 246–249 (2000)
[15] C. Gabbanini, A. Fioretti, A. Lucchesini, S. Gozzini, and M. Mazzoni. Phys. Rev. Lett. 84, 2814–2817 (2000)
[16] Andrew J. Kerman, Jeremy M. Sage, Sunil Sainis, Thomas Bergeman, and David DeMille Phys. Rev. Lett. 92, 033004 (2004)
[17] Andrew J. Kerman, Jeremy M. Sage, Sunil Sainis, Thomas Bergeman, and David DeMille Phys. Rev. Lett. 92, 153001 (2004)
[18] M. W. Mancini, G. D. Telles, A. R. L. Caires, V. S. Bagnato, and L. G. Marcassa Phys. Rev. Lett. 92, 133203 (2004)
[19] D. Wang, J. Qi, M. F. Stone, O. Nikolayeva, H. Wang, B. Hattaway, S. D. Gensemer, P. L. Gould, E. E. Eyler, and W. C. Stwalley , Phys. Rev. Lett. 93, 243005 (2004)
[20] A. Ashkin and et al., “Acceleration and Trapping of Particles by Radiation
Pressure,” Physical Review Letters 24, 156 (1970).
[21] A. Ashkin and et al., “Observation of a single-beam gradient force optical
trap for dielectric particles,” Optics Letters 11, 288 (1986).
[22] S. Chu and et al., “Experimental observation of optically trapped
atoms,” Physical Review Letters 57, 314 (1986).
[23] R. Grimm, M. Weidemüller, and Y. B. Ovchinnikov, “Optical dipole
traps for neutral atoms,” Advances in Atomic, Molecular and Optical
Physics 42, 95 (2000).
[24] Nicolas Vanhaecke, Wilson de Souza Melo, Bruno Laburthe Tolra, Daniel Comparat, and Pierre Pillet,“Accumulation of Cold Cesium Molecules via Photoassociation in a Mixed Atomic and Molecular Trap” Phys. Rev. Lett. 89.063001(2002)
[25] N. Zahzam, T. Vogt, M. Mudrich, D. Comparat, and P. Pillet, “Atom-Molecule Collisions in an Optically Trapped Gas” PhysRevLett 96.023202(2006)
[26] J.-M. Z.-J. J. Dalibard, J. Raimond, ed., Fundamental systems in quantum optics. Amsterdam ; New York : North-Holland, 1992.
[27] Laser Cooling and Trapping of Atoms," J. Opt. Soc. Am. B, 6, 2023(1989).
[28] J. P. Gordon and A. Ashkin, Motion of atoms in a radiation trap," Phys. Rev.
A, 21, 1606(1980).
[29] C. Cohen-Tannoudji and et al., “Dressed-atom description of resonance
fluorescence and absorption spectra of a multi-level atom in an intense
laser beam,” Journal of Physics B 10, 345 (1977).
[30] C. Cohen-Tannoudji and et al., “Dressed-atom approach to atomic motion
in laser light: the dipole force revisited,” Journal of the Optical
Society of America B 2, 1707 (1985).
[31] E. L. Raab and et al., “Trapping of Neutral Sodium Atoms with Radiation
Pressure,” Physical Review Letters 59, 2631 (1987).
[32] D. S. Weiss, E. Riis, Y. Shevy, P. J. Ungar, and S. Chu, Optical molasses and
multilevel atoms: experiment," J. Opt. Soc. Am. B, 6, 2072(1989).
[33] D. Hoffmann, S. Bali, and T. Walker,“Trap-depth measurements using
ultracold collisions”, Phys. Rev.A, 54, R1030–R1033 (1996)
[34] Johanna Nes ，“Cold Atoms and Bose-Einstein Condensates in Optical Dipole Potenitals”(2008)
[35] S. Bali and et al., “Quantum-diffractive background gas collisions in
atom-trap heating and loss,” Physical Review A 60, R29 (1986).
[36] E. Burt and et al., “Coherence, Correlations, and Collisions: What One
Learns about Bose-Einstein Condensates from Their Decay,” Physical
Review Letters 79, 337 (1997).
[37] A. Fioretti, D. Comparat, A. Crubellier, O. Dulieu, F. Masnou-Seeuws, and P.
Pillet “Formation of Cold Cs2 Molecules through Photoassociation”, Phys. Rev. Lett. 80, 4402 (1998).
[38] Nicolas Vanhaecke. Etal., Phys. Rev. Lett. 89.063001(2002)
[39] T. Mukaiyama, et al., Phys. Rev. Lett. 92, 180402 (2004)
[40] R. Wynar, et al., Science 287, 1016 (2000).
[41] D. Wang, B. Neyenhuis, M. H. G. de Miranda, K.-K. Ni, S. Ospelkaus, D. S. Jin, and J. Ye, Phys. Rev. A 81, 061404(R) (2010)